Regenerative heat exchanger for heavy liquids



June 4, 1968 R. H. FELDMElEI-i REGENERATIVE HEAT EXCHANGER FOR HEAVY LIQUIDS Filed Sept. 26, 1966 INVENTOE. ROBERT H. FELDMEIER 5y BM (A United States Patent 3,386,497 REGENERATIVE HEAT EXCHANGER FOR HEAVY LIQUIDS Robert H. Feldmeier, 405 Radcliffe Road, De Witt, N.Y. 13214 Filed Sept. 26, 1966, Ser. No. 581,899 2 Claims. (Cl. 165-11) ABSTRACT OF THE DISCLOSURE A product to product regenerator, for cooling a viscous liquid product which has been pasteurized by a like ra-w product to be pasteurized, has three inclined, concentrically mounted, straight tubes forming two annular passages closed by seals at either end, each annular passage having an inlet and an outlet at opposite ends, the innermost tube being open at both ends for forming visual leakdetecting means and the seals being removable for easy disassembly for cleaning. Two oppositely inclined regenerators may be joined by connecting inlets and outlets at one end, the intermediate tubes being removably jointed between inner and outer passage seals for ease in cleaning.

This invention relates to regenerative type heat exchangers and more particularly to a regenerator having a plurality of coaxially mounted tubes forming annular fluid-conducting passages therebetween.

A regenerator is a heat exchanger used to cool a pasteurized fluid product by running it through a passage with a cold raw product to be pasteurized running in a reverse direction in another passage, the two passages being separated by a heat-conducting wall. Since the hot product must be cooled and the raw product heated at the same time, it is important that the rate of flow in either direction be carefully controlled. With viscous products like cream, ice cream mix, and condensed milk the problem of flow control, by regulating each passage size and the pumping pressure, is more difiicult.

It has been found that a triple tube regenerator in which the tubes are mounted coaxially to form annular passages therebetween is an elficient heat exchanger and it has also been found that the inner annular passage must be carefully regulated as to size to prevent the viscous product from layering or flowing at different rates at different distances from the heat exchange surface of the wall between the two annular passages. To this end, a rod or tube with closed ends has heretofore been used at the center of the exchanger to cut down the size of inner passage and to make it an annular rather than a round passage. This however, presents problems of inspection since, if a leak is present in the inner sealed tube the leakage may spoil and contaminate the prod-uct being run through the inner annular passage.

It is, accordingly, the principal object of the present invention to extend the inner tube at either end beyond the ends of the other tubes and to leave the ends of the inner tube open and visible so that leakage may be detected.

Another important object of the invention is to provide means on the inner tube to support the inner tube along its length intermediate of its ends in coaxial relation to the other tubes.

Still another object is to support the tubes inclined to the horizontal so that leakage in the inner tube will appear more quickly at the lower end of the tube.

Other objects and advantages will become apparent from the following description in conjunction with the appended drawing, in which:

FIGURE 1 is a fragmentary view of two sections of a regenerator according to the invention partly in plan and partly in section;

3,386,497 Patented June 4, 1968 FIGURE 2 is an enlarged fragmentary view of a tube coupling shown in FIGURE 1, the coupling being shown partly in longitudinal section; and

FIGURE 3 is an end view of one of the sections shown in FIGURE 1.

Referring to FIGURE 1, two sections 10 and 10a of a modular regenerator are shown connected together side by side, a portion of section 10 being shown in longitudinal section. Each section comprises an outer stainless steel tube 11 which may be as long as is practical with reference to floor space available and tubing length obtainable. Inside tube 11 and coaxial therewith is a middle tube 12 of the same material and inside tube 12 and coaxial therewith is an inner tube 13 of the same material.

Tubes 11 and 12 form therebetween an annular outer passage 14 for the product to be cooled and tubes 12 and 13 form therebetween an annular inner passage 15 for the raw product to be heated.

In an actual embodiment of the invention tube sizes were: outer tube 2'' OD; middle tube 1 /2" O.D.; and inner tube O.D.; the first two being of No. 18 ga. and the inner tube of No. 20 ga. It will be understood that other combinations of sizes may be used according to the size of the annular passages desired.

The outer tube 11 has a plurality of depressions or dimples 16 formed in the wall thereof which form a series of convexly shaped projections on the inner surface of the tube wall to support the middle tube 12 in coaxial relation with tube 11 along their length intermediate their ends. it will be understod that dimples 16 may be spaced at any convenient distance from one another and one dimple 16 may be angularly spaced from the next as, for example, at degrees.

Adjacent each end of tube 11, a short conductor tube 17 of the same material is welded projecting transversely of tube 11 in fluid conducting connection with passage 14 to form an inlet and outlet for the passage.

At the ends of tube 11 a centrally apertured plate 18 encircles the tube and the tube ends are flared outwardly at 19. Au annular seal 2%) of Teflon or other resilient material encircles the end of tube 12 which projects from the end of tube 11 at both ends and another centrally apertured plate 21 encircles the projecting end of tube 12. Plates 18 and 21 are bolted together at their four corners at 22, forcing the seal 20 against the flared end 19 of tube 11 to effectively seal the end of the annular passage 14 and to support the tube 12 coaxially with tube 11 at its ends.

In order to facilitate assembly and disassembly of the regenerator, the middle tube 12 is provided at each end with an extension tube 12 secured in sealed relation to tube 12 by the coupling 25, best seen in FIGURE 2 and more fully described in Patent No. 2,786,696, issued Mar. 26, 1957, to the same inventor.

Tubes 12 and 12 are each provided with a groove 26 at their adjacent ends in which is seated a split ring 27. An annular seal 28 of Teflon or other resilient material is secured coaxially in place between the tube ends by an internally grooved sleeve 29 and centrally apertured plates 30, 30, encircling the respective tubes are bolted together to bear against the rings 27 squeezing the tube ends together against seal 28.

Each extension tube 12' is provided with a conductor tube 33 welded thereto so as to project transversely therefrom and in fluid communication with pass-age 15. The inner tube 13 projects at each end of the section from the end of extension tube 18', whose outer end is outwardly flared at 34 and a resilient annular seal 35 encircling tube 13 closes the end of passage 15. Centrally apertured plates 36 and 37 encircling tubes 18 and 13, respectively, are bolted together at their corners at 38 to secure the seal at the end of the passage and to support the end of tube 13 centrally within extension tube 18'.

Intermediate of its ends, the tube 13 is provided with a plurality of radially outwardly projecting convexshaped knobs 40 to center tube 13 in tube 12. These knobs are spaced along the tube and successively angularly spaced around it like the dimples 16 in tube 11. The knobs 40 may be formed by welding to the outside of the tube, as shown, or hydraulically formed by forming dimples on the inside surface of the tube 13.

Regenerator section is shown as having an identical section 10a secured to it at one end. The two conductor tubes 17, 17, of the respective sections are welded together as shown as are the two conductor tubes 33 at the same end. It will be apparent from inspection that, since tubes 12 are joined to tubes 12' by the couplings 25, assembly and disassem'bly is easily accomplished.

Both ends of the tubes 13 are open but leakage appears at one end more quickly if the section is inclined slightly from the horizontal. Section 10 is inclined downward from right to left in FIGURE 1 and section 10a inclined downward from left to right so that the regenerator can easily be cleaned by pumping chemical cleaner therethrough. It will be apparent that another section under section 10 may be joined to the right hand (FIGURE 1) end of section 10a and, following this pattern, other sections may be added. The opposite inclination of the two sections is accomplished in the weld between the two conductor tubes 17.

In the combination of sections 10 and 19a shown in FIGURE 1, if the right hand conductor 17 of section 10 in FIGURE 1 is the inlet for the hot pasteurized product the corresponding right hand conductor 17 of section 10a Will be the outlet for the flow through passage 14 of section 10, the two connected left hand conductors 17, and the passage 14 in section 10a.

Since flow in opposite directions in the annular passages 14 and is desirable, the right hand conductor 33 of section 10a is then the inlet for the cold raw product which flows through passage 15 of section 10a, through the joined conductors 33 at the left end, and through passage 15 in section 10 to the right hand conductor 33 of section 10 which is the outlet.

Since the sections are inclined, the left hand end of tube 13 of section 10 is the point watched for leakage into tube 13 of section 10. Similarly, the right hand end of the tube 13 of section 10a is the point of inspection for the latter section.

It will be noted that the middle tube in each section has no dimples or knobs and the joints at the couplings are readily visible. The tubes 11 have the dimples 16 and the tubes 13 have the knobs 40, where leakage is most likely to appear. The tubes 11, however, are on the outside where leaks are readily apparent, while the tubes 13, being open at the end can also be visually inspected.

The annular passages 14 and 15 have annular heat exchange surfaces through the wall of the middle pipe 12, and minimal resistance to a steady and smooth flow is oflfered by the dimples 16 and knobs 40. By selecting proper sizes for the three tubes and proper pumping pressures, layering of the product is eliminated and maximum heat exchange effected. In constructed embodiments of the regenerator as described above, the percentage of cooling of the pasteurized product is as high as ninety percent.

What is claimed is:

1. A product to product regenerative type heat exchanger for cooling a viscous liquid product which has been pasteurized by a like raw product to be pasteurized and simultaneously heating the latter, comprising a straight outer tube of comparatively large diameter supported at a small incline, a middle tube of smaller diameter extending coaxially through the outer tube to form therewith an outer annular product-conducting passage, an inner tube of still smaller diameter extending coaxially through the middle tube to form therewith an inner annular product-conducting passage, the outer tube having inwardly projecting protuberances and the inner tube having outwardly projecting protuberances for spacing the tubes, the inner tube projecting beyond the middle tube at both ends and the middle tube projecting beyond the outer tube at both ends, seals at the ends of the outer tube sealing both ends of the outer passage, seals at the ends of the middle tube sealing both ends of the inner passage, an inlet and an outlet fluid conductor in communication with the outer passage projecting laterally from a respective end of the outer tube, and an inlet and an outlet fiuid conductor in communication with the inner passage projecting from a respective end of the middle tube, the inner tube being open at both ends to provide visible leak detection means, the seals being removable for disassembling the tubes for cleaning, and the middle tube having at each end a removably sealed joint between the sealed end of the outer tube and the middle tube laterally projecting conductor whereby the middle tube may be separately removed for cleaning.

2. The structure defined in claim 1 in combination with an identical structure alongside thereof, one end of each like structure having an outlet conductor connected to an inlet conductor of the other structure and an inlet conductor connected to the outlet conductor of said other structure, one structure being inclined from the horizontal in one direction and the other structure being inclined in a reverse direction from the horizontal, whereby a plurality of similar structures may be connected for the continuous flow of liquid products therethrough.

References Cited UNITED STATES PATENTS 856,140 6/1907 Griesser 141 872,175 11/1907 Griesser 16 5-141 912,671 2/1909 Griesser 165-14 1 1,759,126 5/1930 Mansfield 165-141 1,854,619 4/1932 Mortensen 165-141 2,259,433 10/1941 Kitto 165154 3,323,585 6/1967 Cannon 165-141 FOREIGN PATENTS 754,014 8/1956 Great Britain.

ROBERT A. OLEARY, Primary Examiner.

A. W. DAVIS, Assistant Examiner. 

